Satellites have become invaluable tools in such diverse fields as navigation, communications, environmental monitoring, weather forecasting, broadcasting and the like. Hundreds of man-made satellites now orbit the earth, and each year many more are launched from various nations around the world. Moreover, many homes, businesses and government organizations now use satellite systems on a daily basis for entertainment, communications, information gathering and other purposes.
Modern satellites have a metal or composite frame that houses a power source (e.g. one or more batteries, solar cells and/or the like) and various electronic components, as well as one or more antennas. The components generally include one or more “transponders”, which are clusters containing one or more radio receivers, frequency translators and transmitters. The total bandwidth of the satellite is provided by the number of transponders, each of which may have a typical bandwidth of 30-70 MHz or so.
Unlike conventional analog transponder systems, regenerative payloads perform demodulation and remodulation of uplinked signals, recovering and processing not just the user signal, but also the user data embedded within the signal, enabling the payload to act upon it in a desired manner. Embedded data is most often used for autonomous routing in packet based systems and for security functions, as in many government satellites, or both. In particular, error detection and correction can be performed on demodulated data before it is retransmitted, thereby allowing regenerative satellite payloads to generally have good link performance. These characteristics and others make regenerative payloads the most efficient available in terms of control, bandwidth and power use. Regenerative systems do not typically provide universal signal compatibility as may be available from transponder payloads.
FIG. 1 is an illustration of a block diagram of a regenerative satellite payload communications system 10. The regenerative satellite payload communications system 10 includes an uplink demodulator 12 that receives incoming RF traffic 11. That traffic is forwarded to a time depermute block 14, a symbol derotate 16, a deinterlever 18, and an FEC decoder 20, which operate to extract information from the incoming traffic. The traffic moves forward through a data link layer frame reassembly 22, a multiplexer 24, a packet framer 26, and serializer/deserializer (SERDES) 28, to complete the ingress path 30 to the IP router 32. The egress path 34 begins with SERDES 28, the packet framer 27, the multiplexer 24, and a data link layer frame assembly block 29. The traffic then proceeds through a frame alignment buffer 36, a time permutate block 15, and a modulator 38 transmitting departing RF traffic 40. The time permutate block 15 cycles data through a TDM Map 17 and a TDM DeMap 19 having delay compensation 21.
Regenerative systems have been made backward compatible in some arrangements. While the transition from analog transponder payloads to much more efficient digital transponder payloads is clear, the path to provide even more efficient regenerative payload capability without dropping legacy system users or requiring the satellite to carry significantly more processing electronics has been difficult. To avoid loss of operation and to provide continuous revenue flow, existing satellite customers generally desire to transition transponder end users to regenerative services in a gradual manner, over the many-year life span of an expensive satellite asset.